The present invention relates to a device for charging an energy store. Embodiments describe a combined AC-DC quick charge system.
If both ways of charging, that is AC and DC charging, are to be available optionally in a vehicle, this is ideally realized using a combined vehicle plug device allowing both AC and DC charging. A (single-phase or three-phase) AC charger is usually installed within the vehicle and, with optional DC charging, the DC charger is connected directly to the battery of the vehicle. It is disadvantageous here that the charging process, with direct coupling to the battery, is limited in power due to the battery voltage and the limited current-carrying capacity of charge-plug devices available nowadays. This disadvantage can be eliminated by using a DC/DC transducer within the vehicle, however, additional costs and complexity for elements result. Well-known charging devices are described in DE 10 2011 075 927 A1 and DE 10 2012 206 801 A1.
Further charging devices are shown in [1], [2] and [3]. [1] shows a stationary high-power DC/DC transducer. Additionally, a DC/DC transducer and a DC/AC converter which, however, remain unused when charging, are located within the vehicle. [2] shows a motor converter comprising a boost converter, wherein the DC/DC transducer is also used as a buck converter of the voltage of a DC bus to the battery voltage. [3] shows a concept where a three-phase motor converter and the motor inductances can be used as DC/DC transducer, motor converter or two-phase AC charger. The different modes of operation may be selected using a plurality of switches and combinations of switch positions.
EP 2114714 B1 shows a drive system of a hybrid vehicle comprising a motor and an electric motor which supplies the vehicle with energy. In addition, the drive system comprises a first device for storing energy and a second device for storing energy, each storing electrical energy. A power transducer influences the power exchange between the first device for storing energy and the second device for storing energy. In addition, the power transducer comprises an electronic control unit which monitors the charge state of the first device for storing energy and the second device for storing energy. In addition, the second device for storing energy may be operated by means of a direct or alternating voltage, wherein additional power switches for a bridge circuit are necessitated for an alternating voltage operation (compared to direct voltage operation).